The present invention relates generally toward a drive shaft of a motor vehicle. More specifically, the present invention relates to a collapsible driveshaft of a motor vehicle.
FIG. 1 shows a power train of a motor vehicle generally at 10. The power train includes a motor 12 that transfers torque to a driveshaft 14. The driveshaft 14 transfers the torque generated by the motor 12 to wheels 18 via differential 16 for driving the motor vehicle. To protect vehicle occupants in the event of a collision, the driveshaft 14 is designed to collapse upon itself if the vehicle length is compressed. When the driveshaft 14 does not collapses upon itself, it is known to encroach the vehicle cabin by bending, or otherwise being displaced in an upward direction.
A prior art driveshaft is generally shown at 20 of FIG. 2. The prior art driveshaft 20 is formed from a first tubular member 22 and a second tubular member 24. First splines 26 are formed on an inner surface of the first tubular member 22. Second splines 28 are formed on an outer surface of the second tubular member 24. When mating the first tubular member 22 to the second tubular member 24, the first splines 26 receive the second splines 28 along a coaxial direction as is best represented in FIG. 3. The first splines 26 receive torque from the second splines 28 to rotate the wheels 18 in a known manner. The first and second splines 26, 28 are covered with a boot 30 to prevent contamination from entering the driveshaft 14.
Problems exist with the prior art driveshaft 14 design that have not been overcome. For example, while FIG. 3 shows the first splines 26 perfectly mated with the second splines 28 for expediency, it is impossible to perfectly mate adjoining splines due to a variation in the manufacturing. It is known that small gaps exist between the first splines 26 and the second splines 28 that result in chatter and noise transmitted into the passenger compartment. Without this gap, the first and second tubular member 22,24 could not be assembled due to known variations in manufacturing processes. Furthermore, energy transfer is lost between the first tubular member 22 and the second tubular member 24 due to the spaces that are known to be unavoidable. Additionally, the manufacturing process for forming the splines 26, 28 into the tubular members 22, 24 is costly. The splines 26, 28 are either machined or cold formed into the tubular members 22, 24 causing a manufacturing bottleneck in the assembly process of the prior art driveshaft 14. Therefore, a need exists for a new type of collapsible driveshaft that does not require the slow and costly formation of splines and further eliminates spaces known to exist between existing splines.